Depressive episodes hard to treat in continuous cycling bipolar disorder

By Eleanor McDermid, Senior medwireNews Reporter

Patients with bipolar disorder who switch directly between mania and depression without a period of euthymia have a poor response to short-term antidepressant treatment, study findings indicate.

This is consistent with previous reports that continuous cycling patients do not respond well to long-term treatment with lithium, say Antonio Tundo (Istituto di Psicopatologia, Rome, Italy) and study co-authors.

The researchers studied 101 bipolar disorder patients who received treatment for a depressive episode. They found that just 50.0% of the 22 continuous cycling patients achieved a 21-item Hamilton Depression Rating Scale (HDRS21) total score below 7 after 12 weeks of treatment, compared with 82.3% of the 79 noncontinuous cycling patients.

Continuous cycling patients were also significantly less likely to achieve remission, defined as at least a 50% reduction of baseline HDRS21 score, sustained for 8 weeks, at 40.9% versus 69.6%.

After accounting for age, gender, comorbidity and baseline HDRS21 score, continuous cycling patients had 4.4- and 3.3-fold increased risks of failing to achieve a response and remission, respectively, relative to noncontinuous cycling patients.

HDRS21 scores did decline in the continuous cycling group, on average, but the rate of decline over 12 weeks of treatment was slower than in the noncontinuous cycling group. From a baseline of about 22 points, the average score declined to about 9 in the continuous cycling group, compared with just over 5 among patients with noncontinuous cycling.

Tundo et al suggest that clinicians should be aware of their patients’ historical patterns of mood episodes and remission, “in order to improve their ability to predict the short-term response to [antidepressant] treatment of depressive episode and prognosis.”

No studies have yet looked at alternative treatments to “classic antidepressants, such as second generation antipsychotics or electroconvulsive therapy, for patients with continuous cycling in an acute depressive episode,” the researchers write in the Journal of Affective Disorders.

“So, our results have clinical implications and underscore the urgency to identify new treatment [strateges] for [continuous cycling] depressed patients.”

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